Background technique
As the oil hydraulic circuit of Work machine, adopt load sensing circuit.For the oil hydraulic cylinder in the loop is supplied with enough pressure oil, not only want the lever position of instrumentation oil hydraulic cylinder, also want the hydraulic pressure amount in the instrumentation loop, and calculate the oil hydraulic cylinder load pressure of having considered that the limit is pressed, according to this value of calculating, control supplies to the pump duty (for example seeing patent documentation 1) in loop.But when big load acts on the oil hydraulic cylinder, when engine speed was lower than the rotating speed that can export effective horsepower, electronic control system was controlled pump duty is reduced, to keep the rotating speed of motor.Which kind of situation no matter, by the flow control based on load sensing circuit, not stall of motor in addition, irrespectively moves the object actuator with certain throw of lever with load.
But in some Work machine, the raising of the actuator speed when realizing that shear leg is fallen and the saving of pump duty, employing will press oil to return the regenerative circuit of side (for example patent documentation 2) to the end from the bar side of shear leg oil hydraulic cylinder.In this regenerative circuit, when oil hydraulic cylinder when shrinkage direction moves, press under the high situation at hydraulic pressure cylinder head pressure ratio bar, make working oil from the beginning side turn back to the regeneration of bar side, when the approaching end of contractive action of oil hydraulic cylinder, if bar pressure ratio head is pressed height, then regeneration ending.
Patent documentation 1: Japan is real to open (0001 section, 0002 section, Fig. 2 and Fig. 3) flat 6-84005 number
Patent documentation 2: TOHKEMY 2006-9888 number (0002 section)
Summary of the invention
Therefore, if above-mentioned regenerative circuit has been used to dispose the Work machine of above-mentioned load sensing circuit, can realize in theory and the corresponding suitable pump duty control of oil hydraulic cylinder load, and, can realize the raising of the actuator speed when shear leg is fallen and the saving of pump duty.
But, appropriate load-transducing control as the oil hydraulic circuit of reality and when depositing, can not be carried out in two loops.Below, with Fig. 3 this point being described, Fig. 3 is an example in two loops and the loop of depositing.In the control of load sensing circuit, because the swash plate of using the hydraulic pressure value control pump 2 between shear leg oil hydraulic cylinder 1 and the main valve 3 is (among the figure, A is a Check point, the hydraulic pressure value of this point is sent to pump 2), so, when regenerating, this recovered oil part (part of recirculation) produces difference with the hydraulic pressure value of main valve side.As a result, exist the state of difference, calculating the oil hydraulic cylinder load, so, discharge unnecessary flow (reckoning without the amount of recovered oil part) from pump 2.
As a result, can not realize the original intention of load sensing circuit, be the suitable control of cylinder pressure, and, can not obtain the due pump duty of regenerative circuit and save effect.
The present invention makes in view of the above problems, and the technology that can utilize load-transducing control and regenerative circuit advantage that provides is provided with not producing any problem.
For this reason, the method for controlling pump of Work machine of the present invention, in oil hydraulic circuit, have the hydraulic pressure value that detects the loop, with this checkout value is the hydraulic pressure signal line that the pressure oil mass of oil hydraulic cylinder is supplied with in benchmark control, in above-mentioned oil hydraulic circuit, added regenerative circuit, it is characterized in that, in the way of above-mentioned hydraulic pressure signal line, having disposed the hydraulic pressure value that makes above-mentioned checkout value reduces, this hydraulic pressure value that has reduced is exported to the decompression output mechanism of pump as operation signal, when above-mentioned regenerative circuit is reproduced state, control mechanism makes the hydraulic pressure value that has reduced export from above-mentioned decompression output mechanism, and the discharge capacity of pump is reduced.
Here, in the present invention, detecting the hydraulic pressure value in loop, is the pressure oil mass that oil hydraulic cylinder is supplied with in benchmark control with this checkout value, and this is the pressure oil flow control in the load sensing circuit.That is, the present invention is to be prerequisite with the oil hydraulic circuit that has added regenerative circuit in load sensing circuit.In addition, the regenerative circuit that illustrates in regenerative circuit and the technology before is identical, and, so-called " this regenerative circuit is in reproduced state ", be meant the state that recovered oil flows in regenerative circuit, for example, in the regenerative circuit of shear leg oil hydraulic cylinder, its reproduced state is meant that the pressure oil of hydraulic pressure cylinder head side flows to the state of bar side by regenerative circuit.
As above-mentioned decompression output mechanism,, for example can be reduction valve, safety valve or other pressure regulator tool etc. so long as the hydraulic pressure value of detection is reduced, this has been reduced the mechanism of decompressor that value exports to pump as operation signal get final product.
According to the present invention, can without any problem make load sensing circuit and regenerative circuit and deposit.Promptly, at common state, control with so-called load sensing circuit, the discharge capacity of control pump is when regenerative circuit is in reproduced state, by control mechanism, export to pump as operational order from the decompression output mechanism by the hydraulic pressure value that the decompression output mechanism has reduced, like this, make the oil mass of recovered oil part reduce the control pump flow.Therefore, can be with a loop, obtain the suitable control of the cylinder pressure that undertaken by load sensing circuit and the raising of the actuator movement speed that realizes by regenerative circuit and the effect of improving fuel consumption by the reduction of pump discharge flow rate.
Embodiment
Below, with reference to Fig. 1, the 1st mode of execution as the concrete mode of the present invention is described.The mode of execution that the following describes all is the example that the present invention is used for the loop relevant with the shear leg of hydraulic shovel.Certainly, the present invention is not limited to following mode of execution (also comprising the 2nd mode of execution).For example, the present invention also can be used for the oil hydraulic circuit relevant with arm, the scraper bowl of hydraulic shovel, also can be used for any oil hydraulic circuit of other Work machine.
Among the figure, the 1st, the shear leg oil hydraulic cylinder, the 2nd, main pump, the 3rd, main control valve, the 4th, modulating valve is used in regeneration, and the 5th, as the controller of control mechanism, the 6th, reduction valve.
At first, the loop of present embodiment, with load sensing circuit as prerequisite.That is, be provided with hydraulic pressure value Check point A in the loop, 2 form hydraulic pressure signal line (folder is being established reduction valve 6 the signaling line way, will be described in the back about this point) from this Check point A to main pump.In main pump 2, by the signal from this signaling line, swash plate is controlled, and its discharge capacity is controlled.Like this, formation comes the load sensing circuit of the checkout value of self-hydraulic value Check point A as the operation signal of control pump 2 discharge flow rate.
Next, in the loop of present embodiment, between shear leg oil hydraulic cylinder 1 and main control valve 3, disposing regeneration modulating valve 4.This valve 4 is added one-way valve and has been formed the loop, and this loop is so-called regenerative circuit, that is, in this regenerative circuit, when a side pressure of shear leg oil hydraulic cylinder 1 is higher than bar side pressure, press oil from hydraulic pressure cylinder head effluent to the bar side.Like this, when the state that shear leg (figure do not show) is fallen, the pressure ratio bar side of a side high during, press oil to flow into the bar side from regenerative circuit, like this, realize the raising of falling movement speed of shear leg and the saving of pressing oil.
In addition, when in this regenerative circuit, pressing oil flow, represent the signal of this reproduced state, output to above-mentioned controller 5 with modulating valve 4 from regeneration.Position signal from operating stem 7 also is input to this controller 5.The setting pressure of the shear leg oil hydraulic cylinder 1 corresponding with this position signal (comprising the limit presses) is set in the chart.
In this structure, the feature of present embodiment is in above-mentioned loop, to have disposed the reduction valve 6 as the decompression output mechanism.This reduction valve 6 is configured in from the hydraulic pressure signal line way that above-mentioned hydraulic pressure checkout value point A forms, and when reproduced state, this reduction valve 6 reduces control by throttling to the hydraulic pressure value that detects at an A.This throttling control is to carry out according to the instruction of above-mentioned controller 5, and the instruction of this controller 5 is to export with the signal of representing reproduced state of modulating valve 4 from above-mentioned regeneration by receiving.Its reduction amount, be that amount of restriction is to have considered the amount of regeneration oil mass, its value is set in the above-mentioned chart of controller 5 by calculating in advance.Therefore, controller 5 is extracted corresponding amount of restriction out according to the position signal of operating stem 7 and the signal of expression reproduced state from chart, this amount of restriction is exported to above-mentioned reduction valve 6 as reducing command signal.
Reduction valve 6 slave controllers 5 receive when reducing command signal, after the hydraulic pressure value that detects is reduced by throttling, it are delivered to main pump 2 as load-transducing pressure.As mentioned above, because load-transducing pressure is the operation signal of the head pressure control of main pump 2, so, during reproduced state, 6 pairs of main pumps of reduction valve, 2 output decompression command signals.At the operation signal that has reduced pressure that receives from reduction valve 6 is in the main pump 2 of pressure, controls swash plate based on this pressure, and the amount that has deducted the regeneration oil mass flows out as head pressure.
As mentioned above, in the present embodiment, when the common state of non-reproduced state, carry out common load-transducing control, when descending, when becoming the state of pressing oil regeneration, consider the pressure oil of the recycle sections of regeneration, control lowered pump duty as shear leg.
Therefore, in the present embodiment, in the time of usually,, carry out the suitable flow control of pump 2 by load-transducing control, during regeneration, the control of carrying out improving the movement speed of shear leg oil hydraulic cylinder 1 by regenerative circuit and improving fuel consumption by the pump duty reduction.
And as the structure of device, as long as existing load sensing circuit and regenerative circuit are combined, additional again reduction valve 6 gets final product with controller 5 its controls of instruction.So, needn't just change significantly and can realize existing loop, cost is also cheap.
Below, with reference to 2nd mode of execution of Fig. 2 explanation as another way of the present invention.Present embodiment has roughly the same formation (part of same structure is annotated with same tag, and its explanation is omitted), the structure difference of the output mechanism that just reduces pressure with above-mentioned the 1st mode of execution.
That is, the decompression output mechanism of present embodiment valve 8 safe in utilization reduces the hydraulic pressure value of hydraulic pressure signal line by this safety valve 8.In addition, in the present embodiment, disposing electromagnetic switching valve 9 in the upstream of above-mentioned safety valve 8, by the switching controls of controller 5, in the time of usually when regeneration (non-), the checkout value of A is directly exported to pump, during regeneration, outputs to safety valve 8 sides.In lead to the line of this safety valve 8, formed not the flow controller 10 that pressure is exerted one's influence, and, from being lowered of safety valve 8 the hydraulic pressure value export to pump 2 by one-way valve 11.Here, above-mentioned safety valve 8 then also can dispose above-mentioned one-way valve 11 especially if adopt the solenoid of inverse proportion type, at this moment, from being lowered of safety valve 8 the hydraulic pressure value directly export to pump 2.Which kind of situation no matter, the decompression adjusting of above-mentioned safety valve 8 and above-mentioned the 1st mode of execution are similarly, be to carry out according to the chart that is set in the controller 5, like this, during regeneration, the pressure relief value of having considered the recovered oil part outputs to pump 2 as operation signal from safety valve 8, carries out reduction flow control based on operation signal from pump 2.
Therefore, similarly, in the time of usually,, during regeneration, utilize regenerative circuit and improve the movement speed of shear leg oil hydraulic cylinder 1 and utilize pump duty to reduce and improve the control of fuel consumption in the present embodiment with the normal flow rate control of load-transducing control carrying out pump 2.Certainly, with above-mentioned the 1st mode of execution similarly, needn't change significantly existing loop and just can realize, so cost is also cheap.
The present invention can be used for the oil hydraulic circuit of Work machine.